In recent years there has been a movement from direct cable connection as between a foot pedal and an engine throttle to an electronic connection. An example of such electronic system can be found in the commonly owned U.S. Pat. No. 5,133,321 which is incorporated herein by reference.
Typical components for such a system are a foot pedal, a sensor, and a coupling that couples the foot pedal to the sensor. The sensor senses foot pedal movement and position as between idle and full throttle, and then conveys an electronic signal to the engine's throttle control. The throttle control incorporates a monitor that monitors the signal from the sensor and converts the signal to the appropriate commands for setting the throttle speed.
The system particularly contemplated by this invention is used in trucks. Trucks are largely controlled by government and/or industry regulations and requires designated safety features. Certain of these features are commonly incorporated into the coupling between the foot pedal and the sensor.
The primary objective of the coupling is to couple the foot pedal to the sensor/potentiometer and this is accomplished by a shaft having one end attached to the foot pedal in a manner whereby depression of the foot pedal causes rotative turning of the coupling shaft about its axis. The other end is attached to the potentiometer shaft. Thus as the pedal is depressed the resulting rotation of the coupling shaft causes corresponding rotation of the potentiometer shaft.
It is desirable to control movement of the coupling shaft. The shaft should be prevented from any axial movement and it should be restricted in its rotative movement which in one extreme position represents the foot pedal fully retracted, i.e., nondepressed whereat the engine throttle should be at idle. The other extreme position represents the foot pedal at the full depression and the engine at full throttle. Rotative control is provided by "stops". Thus the shaft is provided with a protrusion. The shaft is encased in a housing. The housing is provided with attachments strategically positioned in the path of the shaft protrusion as the shaft is rotated. Thus the protrusion engages one stop positioned at the extreme rotative position representing idle and a second stop positioned at the opposite extreme rotative position representing full throttle.
Whereas a vehicle foot pedal is manually depressed (by the operator's foot) the return to idle is provided by a spring return. Prescribed safety standards provide for a double spring return. This spring return is preferably incorporated into the coupling. Thus the coupling has become a complex assortment of components starting with the housing and shaft and including numerous bearings, springs, pins, etc. The production of the parts is expensive and the assembly cost adds substantial additional cost.
It is therefore an object of the present invention to provide a fully operable and reliable coupling for vehicle engine control that has reduced parts, less complexity and easier assembly.